Scientists believe they may have found a gene that causes infertility in men.

The gene, known as ZNF214, is thought to prevent some men from producing sufficient sperm cells.

Dutch researchers are carrying out tests on human testicle cells and mice to try to determine exactly how the gene impacts on sperm production, known as spermatogenesis.

They hope that their work will eventually lead to new treatments for infertility.

The gene is located on a chromosome region linked to Beckwith Wiedemann Syndrome.

BWS is a complex disorder which often causes boys to be born with undescended testicles and suffer from infertility as adults.

Dr Judith Gianotten, from the Amsterdam Academic Medical Centre, said: "For these reasons we hypothesised that ZNF214 could be involved in
male subfertility and we decided to test whether this was the case."

Unusual distribution

Her team found an unusual distribution of DNA variants in the gene in men with low fertility, indicating a link.

The scientists then compared the DNA of 77 men with very low sperm counts and 65 men with normal sperm counts.

In three individuals from the infertile group, three new variants of the ZNF214 gene were found. These did not appear among men in the "normal" group.

For two of the men having one of the gene variants, DNA from their parents showed they had inherited the mutation from their mother.

All three appeared normal in other respects and none had any symptom of BWS, although one did have a medical history of undescended testicles
(cryptorchidism).

Impaired production

Dr Gianotten said: "These results suggest that the ZNF214 gene is involved in impaired spermatogenesis, either on its own, or because it causes cryptorchidism
which in turn leads to impaired spermatogenesis.

"In this study, only one of the patients in which a mutation was found reported a history of cryptorchidism. This might indicate the involvement of
ZNF214 in impaired spermatogenesis on its own.

"However, it is also possible that ZNF214 is a disease-causing gene for cryptorchidism."

The fact that the mutation appeared to be inherited from the mother explained how infertility due to impaired sperm production can be passed on to the next generation, said Dr Gianotten.

If it was inherited from the father, then the mutation would be wiped out of the population.

The research was presented at the European Society of Human Reproduction and Embryology annual meeting in Lausanne, Switzerland.